Optimal dosing of dobutamine for treating post-resuscitation left ventricular dysfunction

Objectives: This study was designed to determine the optimal dose of dobutamine in the treatment of post-resuscitation left ventricular dysfunction. Background: Global left ventricular dysfunction following successful resuscitation from prolonged, ventricular fibrillation cardiac arrest, negatively impacts long-term survival. Dobutamine can overcome this global myocardial stunning. Previous data indicate a dose of 10 mcg/kg min improves systolic and diastolic function, but markedly increases the heart rate. Methods: Twenty swine (24±0.4 kg) were randomized to one of four doses (0, 2, 5, and 7.5 mcg/kg min) of dobutamine for the treatment of post-resuscitation myocardial dysfunction following 12.5 min of untreated ventricular fibrillation cardiac arrest. Cardiac function was measured at pre-arrest baseline and serially for 6 h post-resuscitation. Left ventricular function was evaluated by contrast ventriculograms, left ventricular pressures, +dP/dt, Tau, -dP/dt, and cardiac output. Myocardial oxygen consumption and myocardial blood flow were measured to assess the functional significance of any dobutamine-mediated heart rate responses. Results: Left ventricular dysfunction was evident at 25 min and peaked 4 h post-resuscitation. Significant (P<0.05) improvements in ventricular systolic (EF, CO) and diastolic (LVEDP, Tau) function were evident within minutes of dobutamine initiation and persisted at 6 h for the 5 and 7.5 mcg/kg min groups. Tachycardia manifested with all dobutamine doses, but only affected myocardial oxygen consumption significantly (P<0.05) at the highest dose (7.5 mcg/kg min). Conclusions: Dobutamine at 5 mcg/kg min appears optimal for restoring systolic and diastolic function post-resuscitation without adversely affecting myocardial oxygen consumption.